Time to Sputum Culture Conversion and Its Predictors Among Multidrug Resistant Tuberculosis Patients in Tigray, Northern Ethiopia: Retrospective Cohort Study

Abstract

Background

Sputum culture conversion status is a cardinal index of treatment response and patient outcome for MDR TB patients on longer anti-TB drugs. But, there is limited information on time to sputum culture conversion of MDR TB patients on a longer anti-TB treatment regimen. Therefore, this study aimed to evaluate time to sputum culture conversion and its predictors among MDR TB patients in Tigray, Northern Ethiopia.

Methods

A retrospective cohort study was conducted from January 2017 through September 2020 among MDR TB patients in Tigray, Northern Ethiopia. Demographic and clinical characteristics including bacteriological data were extracted from the TB registration book and electronic database in Tigray Health Research Institute. Statistical analysis was performed using SPSS version 25. The time to initial sputum culture conversion was analyzed using the Kaplan–Meier method. Bivariate and multivariate Cox proportional hazards regression analyses were used to identify predictors for culture conversions. P <0.05 was considered statistically significant.

Results

A total of 294 eligible study participants with a median age of 30 years (IQR: 22.75–40) were included. The participants were followed for a total of 1066.7 person months. Sputum culture conversion was achieved in 269 (91%) of the study participants. The median time of sputum culture conversion was 64 days (IQR: 49–86). In our multivariate model, HIV-positive (aHR=1.529, 95% CI: 1.096–2.132, P=0.012), patients new to anti-TB treatment (aHR=2.093, 95% CI: 1.100–3.982, P=0.024) and baseline AFB smear grading of +1 (aHR=1.982, 95% CI: 1.428–2.750, P=0.001) significantly affected time to initial sputum culture conversion.

Conclusion

The median time of culture conversion was 64 days. Moreover, the majority of the study participants achieved culture conversion within the first six months of treatment commencement, which supports predefined standard treatment durations.

Keywords:

• sputum
• smear
• culture
• conversion
• tuberculosis
• multi-drug resistance
• Ethiopia

Data Sharing Statement

All data supporting the findings of this study are available from Tigray Health Research Institute. Moreover, the data are available from Tigray Health Research Institute’s Institutional Review Board (IRB) via [email protected] upon reasonable request.

Ethical Approval and Informed Consent

Ethical clearance and approval was obtained from Tigray Health Research Institute’s Institutional Review Board (THRI-IRB). Likewise, a permission letter was obtained from Tigray Health Research Institute. This study has no direct contact with patients or patient samples, as all data used are available on Tigray Health Research Institute’s database from routine sputum smears and culture follow-up activities. The study was also conducted in compliance with Helsinki Declaration (www.wma.net/en/30publications/10policies/b3/).

Patient Data Confidentiality and Compliance

This study was conducted in accordance with institutional ethical standards and with the 1964 Helsinki Declaration. Each study participant was identified with a unique code before the data extraction process started. Privacy and confidentiality of the participants were kept secure.

Acknowledgments

The authors are grateful to the staff working in tuberculosis bacteriology section for their cooperation in accessing the required data. We are also thankful to the Tigray Health Research Institute for giving us permission to conduct the study.

Author Contributions

All authors made a significant contribution to the conception, study design, execution, and acquisition of data, analysis and interpretation. All authors were involved in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare that there is no competing interest.